virtualbox.org

Host:
Lenovo Z710 Core i7-4700MQ 16 GB RAM Hybrid Graphics (Intel HD Graphics 4600 / NVIDIA GeForce GT 745M)
Qualcomm Atheros AR8171/8175 PCI-E Gigabit Ethernet Controller, Intel(R) Wireless-N 7260 running Windows 8.1
Host IP : 10.200.1.116
VirtualBox 4.3.8 r92456
Host-Only Networks config: VirtualBox Host-Only Ethernet Adapter #2
IP/Gateway : 192.168.10.1 Mask : 255.255.255.0 DHCP Server disabled

Guest OS 1: Windows XP Professional 32 bit Service Pack 3
IP : 192.168.10.50
Mask : 255.255.255.0
Gateway: 192.168.10.1
3 GB RAM
Guest Additions installed

Guest OS 2: Windows 7 Utimate 64 bit Service Pack 1
IP : 192.168.10.51
Mask : 255.255.255.0
Gateway: 192.168.10.1
4 GB RAM
Guest Additions installed

I need bidirectional networking between the 2 guess OS's. Here are some simple ping tests:
Host pinging guest 1: FAIL
Pinging 192.168.10.50 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 192.168.10.50:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)

Host pinging guest 2: PASS
Pinging 192.168.10.51 with 32 bytes of data:
Reply from 192.168.10.51: bytes=32 time<1ms TTL=128
Reply from 192.168.10.51: bytes=32 time<1ms TTL=128
Reply from 192.168.10.51: bytes=32 time<1ms TTL=128
Reply from 192.168.10.51: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.10.51:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

Host pinging gateway: PASS
Pinging 192.168.10.1 with 32 bytes of data:
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.10.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

Guest 1 pinging gateway: PASS
Pinging 192.168.10.1 with 32 bytes of data:

Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128
Reply from 192.168.10.1: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.10.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

Guest 1 pinging guest 2: PASS
Pinging 192.168.10.51 with 32 bytes of data:

Reply from 192.168.10.51: bytes=32 time=1ms TTL=128
Reply from 192.168.10.51: bytes=32 time=1ms TTL=128
Reply from 192.168.10.51: bytes=32 time<1ms TTL=128
Reply from 192.168.10.51: bytes=32 time=1ms TTL=128

Ping statistics for 192.168.10.51:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 1ms, Average = 0ms

Guest 1 pinging host: FAIL
Pinging 10.200.1.116 with 32 bytes of data:

Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 10.200.1.116:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)

Guest 2 pinging gateway: PASS
Pinging 192.168.56.1 with 32 bytes of data:
Reply from 192.168.56.1: bytes=32 time=3ms TTL=128
Reply from 192.168.56.1: bytes=32 time=1ms TTL=128
Reply from 192.168.56.1: bytes=32 time<1ms TTL=128
Reply from 192.168.56.1: bytes=32 time=1ms TTL=128

Ping statistics for 192.168.56.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 3ms, Average = 1ms

Guest 2 pinging guest 1: FAIL
Pinging 192.168.56.50 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 192.168.56.50:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)

Guest 2 pinging host: PASS
Pinging 10.200.1.116 with 32 bytes of data:
Reply from 10.200.1.116: bytes=32 time<1ms TTL=128
Reply from 10.200.1.116: bytes=32 time<1ms TTL=128
Reply from 10.200.1.116: bytes=32 time=1ms TTL=128
Reply from 10.200.1.116: bytes=32 time<1ms TTL=128

Ping statistics for 10.200.1.116:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 1ms, Average = 0ms

==============================================

Bidirectional net access fails between host and guest 1. Guest 2 pinging guest 1 fails, but reverse passes. Please help, this is driving me crazy!

You are working under the assumption that the host-only service uses a gateway. It does not as it was designed to connect the host and the guest while off the network.
Instead of posting all the addresses and that they fail, perhaps you can post what it is you are setting up and we could point you in a better direction.

Perryg wrote:You are working under the assumption that the host-only service uses a gateway. It does not as it was designed to connect the host and the guest while off the network.
Instead of posting all the addresses and that they fail, perhaps you can post what it is you are setting up and we could point you in a better direction.

Thanks for responding Perryg.

I am trying to setup a self contained development environment for offsite use. The ideal configuration is:

Host OS:
Windows 8.1, 16 GB RAM, 1TB Hard Disk

Guest OSs:
WinXP 32 bit Service pack 3, 3 GB RAM - 32 bit development VM
Win7 Utimate 64 bit Service pack 1, 4 GB RAM - 64 bit development VM
Latest version Debian Linux 64 bit, 4 GB RAM - 64 bit development VM

Latest version Fedora Linux 64 bit, 2 GB RAM - Subversion Source code repository
Latest version Gentoo Linux 64 bit, 2 GB RAM - Database server

This configuration covers users' preference of Windows vs. Linux development environment.

Not sure if I should configure VMs with NAT and Host-Only or Bridged networking. Suggestions/recommendations welcome.

Thank you in advance.

Bridged would be easier or at least more simple, but NAT + Host-Only will work locally.

Bottom line is if you expect to connect to the guest directly you would need Bridged or port forwarding on NAT. Very confusing with more than one guest.

Thanks for the suggestions perryg. Your comment regarding "assumptions" lead me to a gross oversight

DAMN Microsoft's built in automatic firewall! The solution for Windows is to add new firewall rules or enable existing ones. Also need to run the wizard to setup file and printer sharing. Could also disable firewall bound to host-only network if you're not familiar with windows firewall rules.

QUESTION: If I have a firewall bound to physical network adapter and disable firewall on virtual adapter (host-only), is host-only network still protected since outside world can't access it? I understand if host is compromised then obviously so is host-only virtual network.

The Linux guests should be straight forward, probably only need to setup samba service.